The instant invention relates to microfilm storage and retrieval systems, and more particularly to a microfilm cartridge assembly for storing microfilm in reel form.
Microfilm storage and retrieval systems are well known in the art. In this regard, microfilm is typically stored in a cartridge assembly comprising a free-spinning reel which is received inside cylindrical retaining walls of a housing. In use, the cartridge assembly is snapped into a retrieval apparatus, wherein the cartridge reel is engaged by a spindle of the retrieval system. The spindle then rotates to wind and unwind the film from the reel for viewing. While the prior art microfilm cartridges are adequate for their intended purpose, there are nevertheless several drawbacks in the prior art designs. The single most significant drawback to the prior art cartridge assemblies is a limitation of the speed at which the film can be wound an unwound from the reel. Since the reel is free to move laterally within the confines of the internal retaining wall of the housing, the edges of the reel are pulled into engagement with the internal retaining wall by the rotation of the film, and the rear flange of the reel is driven into contact with the rear wall of the housing. This engagement causes friction between the edges of the reel and the inner retaining walls of the housing; as well as the rear flange of the reel and the rear wall of the housing. The friction binds rotation of the reel and thus limits the speed at which the film can be wound and unwound. Furthermore, the binding can be a problem in cartridge drives which are old, worn, or out of adjustment. Excessive friction and binding of the reel may cause such machines to jam or malfunction. The friction also generates heat which can melt or deform the structure of the housing and the reel, if the reel is wound too fast. Heat damaged and deformed cartridges need to be replaced to maintain access to the microfilm. Still further, friction causes the reel to vibrate and produce unwanted noise during rapid rotation.
The instant invention provides a microfilm cartridge assembly including an integral post and hub arrangement which is operative for stabilizing rotation of the reel within the cartridge housing, increasing possible rotation speeds, reducing friction, and reducing noise levels. More specifically, the microfilm cartridge assembly comprises a housing having front and rear generally parallel, spaced walls, a centrally located post extending perpendicularly inwardly into the housing from the rear wall, and a cylindrical retaining wall disposed between the front and rear walls. The microfilm cartridge assembly further comprises a reel having a hub centered about an axis of rotation of the reel. The hub of the reel is received on the housing post for rotation within the confines of the walls of the housing. The front wall of the housing includes a central opening for permitting engagement of a retrieval spindle with the reel. The most important aspect of the invention is that the hub of the reel is formed with a depth which is slightly less than the maximum height of the post such that the reel is suspended above the rear wall of the housing when the hub is received on the post. The post is preferably tapered upwardly to a point at its central axis to define a single point of contact with the hub. The hub along with the tapered point of contact permits the reel to float within the housing thereby reducing friction between the reel and the housing walls.
Accordingly, among the objects of the instant invention are the provision of a microfilm cartridge assembly wherein the film on the reel can be transferred at a faster speed than currently possible; the provision of a microfilm cartridge assembly which reduces friction and binding of the reel within the cartridge housing; and the provision of a microfilm cartridge assembly which is substantially quieter than the currently available cartridges.
Other objects, features and advantages of the invention shall become apparent as the description thereof proceeds when considered in connection with the accompanying illustrative drawings.